.add {
    background-image: url(../images/buttons/add.png ) !important;
}

.edit {
    background-image: url(../images/buttons/edit.gif ) !important;
}

.del {
    background-image: url(../images/buttons/del.gif ) !important;
}

.find {
    background-image: url(../images/buttons/find.gif ) !important;
}